One of the most common problems treated by eye physicians is dry eye syndrome. It is believed that over ten million Americans suffer from this condition, which is usually caused by problems relating to the tear film that lubricates the eyes. Tears are formed in several glands around the eye. The water layer is produced in the lacrimal gland under the upper eyelid. Other glands in the lids make the oil and mucus layers. Blinking spreads the tears over the eye. Excess tears drain into ducts in the corner of the eye by the nose.
Problems with the tear film may occur due to the aging process. For example, a person produces less oil (up to 60% less) in the tear film at age 65 as compared to at age 18. The reduction of oil in the tear film may allow water in the film to evaporate faster, which leaves the cornea dry.
The use of plugs to block or reduce drainage into the tear ducts can be an effective step in treating moderate to severe dry eye that is incompatible with artificial tear drops and ointments. By blocking this outflow with a plug, called punctal or punctum plug, the tears tend to remain over the eye for a longer time. Punctal plugs have demonstrated to increase the comfort level and lower the frequency of artificial tear use in most dry eye patients.
The known punctum plugs are typically configured in the form of a cylindrical body with a blind hole extending from one end of the plug to allow the plug to be mounted over an insertion rod of an insertion tool, which is shown, for example, by U.S. Pat. Nos. 5,741,292; 5,643,280; 6,344,047; 6,527,780; and 5,335,871. Upon insertion of the plug into the tear ducts, the insertion rod is used to release the plug from the tool.
While the plugs can be used as a technique to control outflow of tears, active agents are frequently administered at the same time to the eye for the treatment of ocular diseases and disorders. Several examples of punctum plug are shown and described in U.S. Patent Publication No. 20070299516, which are hereby incorporated by reference herein to this application. In at least one example of such plug, an active agent is loaded into the blind bore of such plug.